High capacity portable exchange single bed deionizer

ABSTRACT

A device for the deionization of incoming water. The device includes a tank and a generally hollow distributor tube in that tank for ingress into and downward movement of the incoming water through that tank. Slots adjacent the bottom of the generally hollow tube and near the bottom of the tank are provided for distributing the incoming water out of the hollow tube. There is a bed of mixed bed ion exchange resin within the tank. This bed of resin surrounds the generally hollow tube, through which the incoming water travels upwardly. The water is deionized by the ion exchange resin, as it moves upwardly through the resin, after egress from the slots.

TECHNICAL FIELD

This invention relates to a device and method for the deionization ofincoming water. Particularly, the invention is a device and method forachieving a high operating capacity through the use of the reversal ofwater flow in a monobed or mixed bed ion exchange deionizer, resultingin improved flow kinetics.

BACKGROUND OF THE INVENTION

It is well-known in the art that deionized water can be created bymoving tap water through an ion exchange resin bed. In one method,resins fill much of a cylindrical tank. The resins can be of a mixed bedtype. For the purposes of this invention, a “mixed bed resin” is a blendof a cationic and an anionic resin, in an equivalent ratio of 1:1.

In such systems and methods, water enters the top of the cylindricaltank, and moves downwardly through the resin within the tank. When thewater has moved through the resin and reached the bottom of the tank, ithas been deionized (DI).

At this point, the deionized (DI) water flows into slots at the bottomof a hollow tube. The inside of the hollow tube contains no resin, butis typically surrounded by the resin within the tank. After entering theslots at the bottom of the tube, the deionized water moves upwardlythrough the hollow tube, and out of the tank.

High purity water can also be prepared by deionization through reverseosmosis. In high purity water systems, the ion exchange resin bed andreverse osmosis deionization technologies may be used either separatelyor together.

Many moderate to medium volume users of high purity water systems useion exchange resin systems. Typically, two kinds of ion exchange resinsare used for water deionization. The first kind of resin is a cationicresin, which removes cations from the water. The second kind of resin isan anionic resin, which removes anions from the water. These resins areeventually exhausted, lose their ability to deionize water, and thusneed to be regenerated. These moderate to medium users of high puritywater systems depend upon local service companies. In connection withsuch services, a tank with exhausted resin is replaced by a tank withfresh or regenerated resin. The service then regenerates the exhaustedresin, using an acid such as hydrochloric acid or sulfuric acid forcationic resins, and caustic, such as sodium hydroxide, for the anionicresins. The regeneration process in such portable exchange systems takesplace off site in a regeneration facility of the service provider.

There are many different versions of such prior art systems. As notedabove, reverse osmosis systems may be used independently, and are viablealternatives for the preparation of high purity water. However, reverseosmosis systems are often higher in cost, require additionalpretreatment and storage equipment, and typically rely upon a final,resin bed “polisher” tank to provide high purity water.

Resin-based systems are also common, and are typically used where highercapacities are required. A first such resin-based system has two tanksconnected in series. The first tank contains a cationic resin, and thesecond tank contains an anionic resin. Under such an arrangement, bothsuch tanks are typically exhausted simultaneously. The quality of wateris determined by its specific resistance; the higher the specificresistance, the higher the quality of the water. Commonly, the two tanksare removed when the specific resistance of the deionized water hasfallen to about 20,000 ohms-cm.

Another resin-based system has two tanks connected in series, and bothof these tanks contain a mixture of an anionic and cationic resin,otherwise known as a “mixed-bed” resin. This type of system, usingidentical tanks, provides for a main deionization tank, followed by aso-called “polisher” tank. This type of system also provides for aback-up tank, in essence a second deionization tank, between the maintank and the polisher tank, to enable deionization to continue even inthe event that the first tank fails or is exhausted. These types ofsystems are typically used where higher water purity qualities arerequired. The first tank is removed and replaced with a tank containingregenerated resin, when the specific resistance of the deionized waterhas fallen to about 200,000 ohms-cm.

A third type of resin-based system is a hybrid of the above twodescribed resin systems. Particularly, this third system includes onetank having a cationic resin, a second tank having an anionic resin, anda third tank having a mixed bed resin. The first two tanks are theso-called “worker” tanks, while the third tank is the “polisher” tank,to achieve high levels of water purity.

The flow pattern on all of these prior art systems are like the priorart systems shown in FIG. 2, i.e., the “down-flow” type, where theunpurified water enters the tank and moves downwardly through the resinfor deionization.

SUMMARY OF THE INVENTION

The invention is a device and method for deionizing water. The firstaspect of the invention comprises a device for the deionization ofunpurified water. The device comprises a tank for containing a resin.The device also includes a generally hollow distributor tube in the tankfor ingress into and downward movement of the unpurified water throughthe tank.

Slots are positioned adjacent the bottom of the generally hollow tube,and near the bottom of the tank, for distributing the unpurified waterout of the hollow tube. After egress from these slots, the water movesupwardly through a bed of purifying resin within the tank. This resin inthe tank surrounds the generally hollow tube, but no resin is containedwithin the tube. The water moves through the resin in an upwarddirection. After it has moved through this resin, the water isdeionized.

In another aspect of the invention, the generally hollow tube ispositioned substantially in the axial center of the tank. In stillanother aspect of the invention, the openings adjacent the bottom of thegenerally hollow tube are rectangular slots. In yet another aspect ofthe invention, the bed of ion exchange resin is a mixed bed resin.

In the method of the invention, incoming water is deionized by treatmentwithin a tank. The method comprises placing unpurified water into thetop of a generally hollow distributor tube that is positioned within thetank. This unpurified water moves downwardly through this tube.

When the incoming water reaches the bottom of the generally hollowdistributor tube, it exits the tube through slots adjacent the bottom ofthe tube. After exiting the slots, the water is moved upwardly through abed of ion exchange resin within the tank. In this way, the water isdeionized by the resin.

In another aspect of the method, the generally hollow tube is positionedsubstantially in the axial center of the tank. In yet another aspect ofthe method, the openings adjacent the bottom of the generally hollowtube are rectangular slots. In still another aspect of the invention,the purifying resin is a mixed bed resin.

It has been found, surprisingly, that the reversal of the flow of waterthrough the resin-containing tank both extends the operating capacity ofthe resin, and produces a better quality of highly purified water.

Particularly, comparing the device and process of the invention totypical down flow mixed bed ion exchange deionizers, 50-60% higheroperating deionization capacity is achieved through a monobed (or mixedbed) ion exchange resin bed of the present invention's single tankconfiguration. The process incorporates improved kinetics through themixed bed ion exchange resin bed utilizing a bi-lateral flow patternupwardly through the resin bed. The water produced is of a higherquality than water produced in most typical two bed systems. Two bedsystems produce water having, on an average, 200,000-1,000,000 Ohm-cm ofspecific resistance. In contrast, the present invention provides waterin the range of 8,000,000 Ohms at the start to 200,000 Ohms, the reverseof a typical two separate bed system. The cationic and anionic resincomponents are in a consistent 1:1 equivalent (40%-60% by volume)mixture. Thus, the resins are exhausted uniformly in a 1:1 ratio,providing almost neutral pH in a perfectly deionized water.

Furthermore, this process provides significant economic advantages todeionized water service companies/dealers and to the end user, becauseonly a single tank is being used to incorporate a two bed system.Regeneration is accomplished in a single regenerator vessel. Thus, theprocess minimizes the amount of inventory for service tanks and resins,minimizes the cost of original regeneration capital equipment, andimproves operating economics.

In a typical system design for this invention, two tanks are connectedin series. The first tank is the upwardly flow high capacity deionizer,followed by a typical down flow mixed bed polisher tank. Upon exhaustionof the first “high capacity” tank, the secondary tank is moved up andconverted to an upwardly flow configuration, and a new polishing tank isinstalled. This moved up tank is found to yield an additional 50%-60%capacity in this system configuration. Only a one tank exchange isneeded, thus providing customers and dealers with added economicalbenefits.

In contrast, in a typical two tank, separate beds system, two tanks arereplaced during each exchange. These systems require an additional thirdpolishing tank as a back up, adding to the expense of such systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a device in accordance with the invention.

FIG. 2 is a sectional view of a prior art device.

FIG. 3 is an enlarged view of an upper part of the hemispherical headportion at the top of the tank of the device of FIG. 1.

FIG. 4 is a perspective view of an upper distributor basket.

FIG. 5 is an enlarged view of the lower portion of the generally hollowdistributor tube shown in FIG. 1, and the slots at the bottom of thistube.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

This invention is susceptible of embodiments in many different forms.The specification and drawings describe and depict in detail a preferredembodiment of the invention. This disclosure is to be considered as oneexample of the invention. This disclosure is not intended to limit thebroad aspect of the invention to the embodiments illustrated.

Referring to the drawings, FIG. 1 shows a sectional view of a device 10in accordance with the invention. The device 10 of FIG. 1 differs fromthe prior art device of FIG. 2 in one important respect. Particularly,the prior art device of FIG. 2 is used to deionize water that movesinitially into the top of the tank, then down through the resin, theninto the slots at the bottom of the hollow tube, and then upwardlythrough the tube and out of the tank.

In contrast, in the present invention, i.e., in the otherwise identicaldevice of FIG. 1, the water is deionized by moving initially into anddownwardly through the hollow tube, out of the slots at the bottom ofthe hollow tube, and then upwardly through the resin and out of thetank. While such so-called counterflow systems may exist for watersoftening systems, they do not exist in high-purity water systemsutilizing mixed bed resins. High purity water is critical for certainusers, such as laboratories, manufacturers of printed circuit boards,plating companies, and other industries. For purposes of this invention,high purity water is defined as water that is deionized.

The invention is a device 10 and a method for deionizing water. Thefirst aspect of the invention comprises a device 10 for the deionizationof incoming water. The device 10 comprises a generally cylindrical tank12 for containing a resin 14. The tank has preferred dimensions ofapproximately thirteen (13) inches in diameter, and approximatelyfifty-four (54) inches in height, however, other suitable tank sizes canbe utilized. The resin 14 may be any suitable water-purifying ionexchange resin, but the preferred resin 14 is a so-called “mixed bed”resin. Several commercially available “mixed bed” resins are suitablefor the present invention, but a preferred mixed bed resin 14 for thepresent invention is made by the Rohm & Haas Company under its CatalogNo. UP-4150. As may best be seen in FIG. 1, this high capacity mixed bedresin 14 does not fill the cylindrical tank 12, but instead fills thetank to a point roughly at the bottom of the hemispherical head portion16 that defines the top of the tank 12. The mixed bed resin 14 istypically a cationic/anionic mixture, and has volume percentages ofabout 40% cationic and 60% anionic.

The device 10 also includes a generally hollow distributor tube 18. Thisgenerally hollow distributor tube 18 is preferably made of a rigidpolymer, and is preferably positioned approximately in the axial centerof the tank 12. The generally hollow distributor tube 18 provides foringress of the incoming water into, and downward movement through, thetank 12. In the attached FIGS. 1 and 2, the paths of the water movingthrough the device, and the direction of flow of that water, are bothindicated by arrows.

Slots 20 are formed in generally hollow tube 18. As may best be seen inFIG. 1, these slots 20 are also positioned near the bottom of the tank12. Specifically, the slots 20 should extend upwardly about three tothree and one-half (3-3½) inches from the bottom of the generally hollowdistributor tube 18.

In this preferred embodiment, these slots 20 have a generallyrectangular configuration. The slots 20 take the downwardly moving waterand discharge that water into the bottom of the tank 12, and upwardsinto the bed of resin 14. This water movement is best depicted by thetwo curved, bottommost arrows shown in FIG. 1.

The water is continuously discharged through these slots 20 aspressurized water enters the tank 12 and its generally hollowdistributor tube 18. As the water is discharged through these slots 20,it forces the remaining water in the bed of resin 14 upwardly throughthat bed, where it becomes deionized.

It will be understood that while the resin 14 in the tank 12 surroundsthe generally hollow tube 18, no resin 14 is contained within thegenerally hollow tube 18.

Details of the various other elements of the device 10 are shown inFIGS. 3-5. FIG. 3 depicts an enlarged view of an upper part of thehemispherical head portion 16 at the top of the tank 12. The waterenters the tank 12 through a polymeric tank closure or manifold 24. Thetank closure 24 includes an inlet 26 and an outlet 28. Both the inlet 26and the outlet 28 are preferably ¾″ HPT quick connects.

The base of the tank closure 24 has a threaded portion 30 that securesthe closure 24 to complementary threads 32 near the top of thehemispherical head 16 of the tank 12. Typically, these are #8 threads,and they extend for about 2½″ along the exterior of the tank closure 24.

As may also be seen in FIG. 3, an O-ring 36 is seated between the tankclosure 24 and the top of the tank 12, and this O-ring 36 provides awater-tight seal for the tank 12.

The top of the generally hollow distributor tube 18 is secured to thetank closure 24. This securement takes place by pushing the top of thisdistributor tube 18 into a central hole of the tank closure 24. Theinlet 26 of the tank closure 24 provides, with the hollow distributortube 18, a continuous path for the incoming water to the tank 12. As mayalso be seen in FIG. 3, a second O-ring 34 provides yet another watertight seal, this seal being positioned between the outside of thegenerally hollow distributor tube 18 and a portion of the tank closure24.

As may be seen in FIG. 3, an upper distributor basket 38 is secured tothe lowest extremity of the tank closure 24. Details of the upperdistributor basket 38 are shown in FIG. 4 Typically, the securement ofthe basket 38 to the polymeric tank closure 24 is facilitated by the useof any one of several suitable adhesives.

The upper distributor basket 38 is preferably made of a hard polymericmaterial. Like the generally hollow distributor tube 18, the upperdistributor basket 38 includes thin, rectangular slots 40 through whichwater can flow. Like the slots 20 in the distributor tube 18, theseslots 40 are small enough to prevent any of the resin 14 from passingthrough them. Hence, the resin 14 cannot leave the tank 12 with theexiting water, and remains in its proper place within the tank 12.

As the water moves upwardly through the resin 14 and into the empty,hemispherical portion 16 of the tank 12, it has been deionized and readyto leave that tank 12. The deionized water at the top of the tank 12leaves the tank 12 through the continuous path formed by the upperdistributor basket 38 and the outlet 28 of the tank closure 24.

It should be understood by those skilled in the art that the tank andother elements of the device 10 of FIG. 1 may be typically placedin-line with other tanks, for example another identical tank, and thenwith a mixed bed polisher.

In the method of the invention, incoming water is deionized by treatmentwithin the tank 12. The method comprises placing incoming water into thetop of a generally hollow distributor tube 18 that is positioned withinthe tank. This unpurified water moves downwardly through this tube 18.

When the incoming water reaches the bottom 22 of the generally hollowdistributor tube 18, it exits the tube 18 through slots 20 adjacent thebottom 22 of the tube 18. After exiting the slots 20, the incoming wateris moved upwardly through a bed of ion exchange resin 14 within the tank12. In this way, the incoming water is deionized by the resin 14.

In another aspect of the method, the generally hollow tube 18 ispositioned substantially in the axial center of the tank 12. In yetanother aspect of the method, the slots 20 adjacent the bottom 22 of thegenerally hollow tube 18 are rectangular slots. In still another aspectof the invention, the purifying resin is a mixed bed resin.

As compared to the prior art resin systems of FIG. 2, i.e., theso-called “down-flow” systems, it has been surprisingly found that themere reversal of the water flow in the direction shown in FIG. 1provides substantial operating advantages. First, when comparing systemsusing two high capacity mixed bed resin tanks and one mixed bedpolishing tank, all of the tanks being in series, the invention usingthe water flow path of FIG. 1 provides from 55 to 65% additional waterpurification capacity, before exhaustion of the resin, than otherwiseidentical “down-flow” systems. While the reasons for this are unclear,it is speculated that the invention of FIG. 1 somehow results inimproved utilization of the ion exchange sites of the resin. This allowscontinuous classification of the resin beads on the bed and more uniformdistribution or stratification of the bed.

This system also reduces the number of service calls necessary fromregeneration services, and lowers the cost per gallon of thepurification process. In fact, regeneration plant costs can be cut asmuch as 60% by eliminating up to two additional regenerator and chemicalneutralization units.

Additional advantages include higher quality or higher purity water.Particularly, in tests performed after use of the present invention, itwas found that the water can be maintained at a specific resistance ofover 10 megohms-cm.

In contrast, dual bed resin down-flow water purification systems (onetank containing cationic resins and another containing anionic resins)initially have a specific resistance of only about 1-2 megohm-cm. Inaddition, this specific resistance is not maintained for any appreciablelength of time, but instead the water quality declines to a specificresistance of about 500- and then down to 200-kilo-ohms for the majorityof the service run.

There is another advantage over a prior art dual bed resin.Specifically, the present mixed bed resin system lowers the amount ofresin that must be retained in inventory, and also allows regenerationof the resin in a single regeneration tank. As a result, theregeneration process is always the same, and better quality controlinvariably results. Service providers can also minimize theirexpenditures for regeneration equipment, resin and tank inventories, andraw materials, thus providing customers with a more economical solution.

The present systems are modular and portable, thus allowing flexibilityin designs and configurations. This flexibility permits custom design ofsystems for virtually any moderate to medium volume water purificationplant. One tank, as shown in FIG. 1, would be adequate to purify water.More typically, however, as noted above, two main tanks are used inseries, with an additional polishing tank. In addition, additional tankscan be added to the two main tanks normally used in series, such thatthere are three or four main tanks in series, in order to accommodatehigher volume users.

It will be understood that, given the above description of theembodiments of the invention, various modifications may be made by oneskilled in the art. Such modifications are intended to be encompassed bythe claims below.

What is claimed is:
 1. A device for the deionization of incoming water,comprising: (a) a tank; (b) a generally hollow distributor tube in saidtank for ingress into and downward movement of said unpurified waterthrough said tank; (c) openings adjacent the bottom of said generallyhollow tube and near the bottom of said tank for distributing saidunpurified water out of said hollow tube; and (d) a mixed bedion-exchange purifying resin within said tank, and surrounding saidgenerally hollow tube, through which said unpurified water travelsupwardly, and is deionized to a high purity water by said mixed bed ionexchange resin, as it moves upwardly through said resin, after egressfrom said openings.
 2. The device as set forth in claim 1, wherein saidgenerally hollow tube is positioned substantially in the axial center ofsaid tank.
 3. The device of claim 1, wherein said openings adjacent thebottom of said generally hollow tube are rectangular slots.
 4. A methodfor the deionization of incoming water within a tank, comprising: (a)placing such water into a generally hollow distributor tube within saidtank, for ingress into and downward movement of said unpurified waterthrough said tube; (b) withdrawing water from said generally hollowdistributor tube through openings adjacent the bottom of said generallyhollow tube, and near the bottom of said tank; and (c) moving said waterupwardly through said tank, and through a mixed bed of ion exchangeresin within said tank, so that said incoming water is deionized to ahigh purity water by upward movement through said mixed bed resin afteregress from said openings.
 5. The method of claim 4, wherein saidgenerally hollow tube is positioned substantially in the axial center ofsaid tank.
 6. The method of claim 4, wherein said openings adjacent thebottom of said generally hollow tube are rectangular slots.
 7. A methodfor the deionization of incoming water within a tank, comprising: (a)placing incoming water into the top of a tank; (b) moving said incomingwater to the bottom of said tank; and (c) moving said incoming waterupwardly through said tank, and through a mixed-bed of ion exchangeresin within said tank, so that said incoming water is deionized to ahigh purity water by upward flow through said mixed-bed resin.
 8. Themethod of claim 7, wherein said incoming water is moved to the bottom ofsaid tank by a generally hollow tube.
 9. The method of claim 8, whereinsaid generally hollow tube is positioned substantially in the axialcenter of said tank.
 10. The method of claim 8, wherein said generallyhollow tube includes openings adjacent the bottom of said generallyhollow tube and wherein said openings are rectangular slots.